1. Field of the Invention
The instant disclosure relates to a device and a method for measuring the power consumption; in particular, to a device and a method by using sensing the voltages and the currents on the AC power line in a contactless way for measuring the power consumption.
2. Description of Related Art
The conventional household power meter, adapted for accumulation of the used electric power, usually directly measures the current and the voltage by using electric conductors for measuring the electric power consumption. Practically, the power consumption calculation is based on the real power (or active power). The real power indicating the power consumption is related to the power factor. For a resistive load, the power factor is 1. However, for a non-resistive load, such as an inductive load or a capacitive load, the power factor is not 1 when feeding electric power into the non-resistive load. Conductive-type measurement can obtain the actual current, the actual voltage and the power factor. However, the conductive-type measurement is a contact-type measurement which introduces conduction loss during measurement. And, this measurement has the potential risk of electric shock. Therefore, the design of the contact-type measurement is more complicated and the installation could be cumbersome.
Additionally, the current clamp meter can contactlessly measure the current on the power line. Compared to the contact-type measurement, the current clamp meter has the feature of easy to use and avoiding the danger of the electrical leakage in contact. However, the current clamp utilizing contactless measurement can only measure the real-time current, but the real-time voltage cannot be obtained at the same time, thus the power factor cannot be obtained. Because the power factor cannot be obtained, the real power is not possible to be obtained. In other words, for the circumstance of the power is not equal to 1, the current clamp meter utilizing contactless measurement cannot obtain the real power.